Heat-copying process



United States Patent O 3,280,735 HEAT-COPYING PROCESS Bryce L. Clark andCarl S. Miller, St. Paul, Minn., assignors to Minnesota Mining andManufacturing Company, St. Paul, Minn., a corporation of Delaware FiledApr. 13, 1964, Ser. No. 359,247 11 Claims. (Cl. lOl-149.2)

This application is a continuation-in-part of our applica-tion SerialNumber 843,161, filed September 29, 1959 and now abandoned.

This invention relates to the thermally induced reproduction of graphicoriginals and to materials employed therein, and is particularlydirected to novel procedures involving heat-induced transfer of imageforming components, and to novel products employed therein.

Chemically reactive heat-sensitive copy-papers and thermographicreproduction processes in which such papers are employed have becomewidely known, for example in the reproduction of typewritte'ncorrespondence and other office records. In one commercial application,the copy-paper is placed in heat-conductive pressurecontact with theorigin-al which is then briefly intensely irradiated, e.g. withradiation rich in infrared. Heating occurs at the radiation-absorptiveimage areas of the original, accompanied by a visible reaction atcorresponding Iareas of the copy-paper. yA direct or positive copy isproduced immediately, without further chemical or other processing.

Physically heat-sensitive copy-papers useful in thermographic copyingare also known. One form consists of a dark-colored paper or lm baseprovided with an opaque surface coating of a transparent fusiblematerial in particulate form. Fusion of the particles at the heatedareas renders the coating permanently transparent, permitting the darkbackground -to be seen. Another form depends on flow of the fused andliquefied coating, e.g. into the absorbent carrier web, to provide avisible change at the heated area. As with the chemical paper, theapplied heat-pattern causes the formation of a reproduction of thegraphic original without further chemical or other processing.

The present invention likewise makes possible the formation ofreproductions of graphic originals in a singlestep simplified processrequiring no subsequent chemical or yother treatment. The resultant copyis not susceptible to further coloration on subsequent heating, so thatbackground darkening is avoided. Simplified procedures for providing thenecessary temperature are made possible. Other distinctions andadvantages will be made apparent hereinafter.

The invention 'broadly involves the transfer of a normally stably solidimage-forming material in vapor form from a supply sheet to a suitablereceptor surface in a pattern determined by the graphic representationsof the original. In one form of the invention the image-forming materialis transferred to a receptor sheet containing a color-forming reactantfor said material, the two then reacting to form visibly distinct imageareas. Where the vaporizable material is itself strongly colored, noreactant is required on the receptor sheet. The vaporizable material maybe incorporated in the ink with which the graphic original is printed,either prior to or after printing; or it may be supplied as a componentof the printed sheet or of a separate vapor supply shee-t.

The invention will now be further described in connection with theaccompanying drawing in which the several figures indicate in partialcross-section various combinations and composites of components asemployed in producing copies of reproductions of graphic originals bythe various processes indicated.

In FIGURE 1 there is provided a graphic original 10 comprising a support11 on which has been printed or otherwise deposited inked image areas12. A page of a book printed with an oil base carbon ink on a whitepaper is one example of such an original. Another example is alithographie printing plate, having oil-receptive image areas andwater-receptive background areas on a treated aluminum panel. Typically,the image areas may include a hardened gelatin substrate and a resinousor oleaginous oil-receptive surface coating.

Against the printed surface of lthe original 10 there is placed a vaporsupply sheet 13, one form of which consists of a thin porous paperpartially impregnated with a vaporizable phenolic compound, e.g.pyrogallol. Heat is applied to the composite, as indicated lby the wavyarrows 14, typically by passing the composite through a -heated mangleor ironing machine. Vapors from the vapor supply sheet 13 are condensed,presumably by absorption, on the inked image areas of the printedoriginal. The thus treated original is identified in FIGURES 2 and 3 astreated original 10a and itself serves as a vapor supply sheet insubsequent processing.

It will be understood that the spacing between sheets indicated in theseveral figures of the drawing is for purposes of clarification and thatin practice the sheets are in surface-tosurface contact.

The vapor supply sheet 13 is next replaced yby a receptor sheet 15, asshown in FIGURE 2, and the new composite is again heated, for example bypassing through the heated mangle. The receptor sheet 15 comprises asupport 16 having a reactive layer 17 within or on the surface thereof.Where pyrogallol is employed as the vaporizable material, the layer 17may suitably comprise ferric stearate. y

When the receptor 15 is removed from the surface of the treated original10a, it is found to have a visible image pattern corresponding to theimage areas of the graphic original and indicated as reacted image areas18 in FIG- URE 2. The reproduction appears as a mirror image as viewedfrom the treated side of the sheet 15, i.e. from the surface previouslyin contact with the image area of the original. Alternatively, the imagemay be viewed as a direct image from the reverse side of the receptor 15when the support member 16 is transparent.

In FIGURE 3 the treated original 10a, prepared as described inconnection with FIGURE 1, is placed in contact with an intermediatetransfer sheet 19 and the composite is again heated. During this processthe reactive material, which was originally transferred from the vaporsupply sheet 13 to the inked areas of the graphic original 10 asdescribed in connection with FIGURE 1, is again vaporized andtransferred to the transfer sheet 19, where it is retained in condensedor absorbed form as indicated at 20. The transfer sheet 19 is thenremoved from the graphic original. The image areas 20 are clearlyvisible when a strongly colored vaporizable component is used, and forma visible direct positive or right-reading copy of the original asviewed through the transfer sheet 19, which for this purpose musttherefore be transparent.

Where .a reactant vaporizable material is employed, the imaged surfaceis next placed in contiguity with the treated surface of a co-react'ivereceptor sheet 15 as illustrated in FIGURE 4, and the composite islheated as before, causing retransfer of vaporized reactant from thetransfer sheet 19 to the receptor 15, with formation of reacted visibleimage areas 21 corresponding directly to the image areas of the graphicoriginal 10. In the latter procedure the transfer sheet need not betransparent and the mirror image formed thereon need not be a visibleimage. The same procedure is applicable with non-reactive, directlyvisible vaporizable image-forming material except that in this instancea non-reactive receptor sheet may be employed.

Where the graphic original is as described in connection with theprocess of FIGURE l, and the vapor supply sheet 13 contains pyrogallol,also as described under FIGURE l, the transfer sheet 19 may convenientlybe a waxed or paraffined paper, and the receptor sheet 15 will thensuitably comprise a normally stable layer or coating of ferric stearate.

The procedure indicated in FIGURE 5 employs radiation with highintensity light rays, preferably rich in infrared, in place of directheating. As shown in the figure, the graphic original having printedimage areas 12 is placed with its unprinted surface against the vaporsupply sheet 13 which is in contact with the reactive layer 17 of thereceptor sheet 15. The image and background areas of the surface of theoriginal 10 are differentially absorptive of radiation 23, which aspreviously indicated may be largely infrared radiation. The composite isbriefly subjected to intense irradiation, resulting in a preferentialheating effect at the printe-d image areas, causing the -transfer ofvaporized reactant from the supply sheet 13 to the coreactive treatedsurface layer 17 of the receptor sheet 15 and resulting in formation of-reacted image areas 21 corresponding directly with the printed imageareas 12 of the original. Some of the reactant is simultaneouslytransferred to the unprinted surface of the original where it condensesto form reactant image areas 22 and from whence it may subsequently betransferred to form visible image areas 21 on a receptor sheet 17 asshown in FIGURE 10.

Apparatus suitable for momentarily intensely irradiating the compositieas just described may conveniently consist of a line source of lightincluding a tubular lamp having a linear filament and mounted within afocused reflective housing for progressive exposure of the printedsurface of the original, all as described in Miller United States PatentNo. 2,740,895. Another suitable form of apparatus is described inKuhrmeyer et al. United States Patent No. 2,891,165.

In a simplified version of the foregoing, the vapor supply sheet and.graphic original are combined in a single sheet material, e.g. bysurface-treating the rear or unprinted surface lof the original withpyrogallol or other vaporizable component, or by printing or otherwiseapplying an original graphic representation to a previously impregnatedvapor supply sheet. The procedure is illustrated in FIGURE 6.k Theradiation-absorptive inked image areas 12 are inscribed on the vaporsupply sheet 13a, the opposite surface of which carries a layer 13b ofvolatilizable normally solid reactant. The sheet is placed against thereactive surface 1'7 of a receptor sheet and is briefly exposed tointense radiation 23, causing vaporization and transfer of reactant andformation of visible image areas 21. The procedure is repeated withadditional receptor sheets 15 in making a number of copies.

FIGURE 7 indicates a modification in which `the image areas 12C of thegraphic loriginal 10c are initially formed of an ink which lcontains avaporizable strongly colored image-forming material. The sheet is placedwith the inked surface against a receptor sheet Z4. The application ofheat, as with a heated mangle or Flatiron, causes transfer of thecolored material in vapor form from the inked areas to the correspondingareas of the surface of the copy paper, and results in the formation ofimage areas a. In this instance the resulting reproduction will occur asa mirror image of the original when viewed from the treated surface, butmay be viewed as a direct (rightreading) reproduction in the case of atransparent receptor sheet, or may be produced as a direct reproductionon an opaquereceptor sheet by a two-step transfer procedure aspreviously described.

The use of inter-reactive volatilizable component and receptor sheetwill be seen to make possible the selection of a wide variety ofvolatilizable components which may be either intensely -colored orcolorless. Reactants may be selected so as to provide intensely coloredand permanent image areas. Effective images may be produced withextremely slight amounts of vaporizable reactant, so that large numbersof copies may be produced from a single treated original. Simple andreadily available sources of heat may be effectively employed. Thereceptor sheet coating may be applied to paper, film, fabric, wood orvarious other surfaces, for reproduction thereon of handwritten orprinted intelligence, engineering drawings or designs, etc.

Ferric stearate is a preferred compound for use in the reactive receptorsheet or copy paper in conjunction with volatilizable phenolicimage-forming materials such as pyrogallol. A suitable form of ferricstearate is prepared as follows: To an aqueous solution of three mols ofthe sodium soap of commercial triple-pressed stearic acid ofmelting-point approximately 53 C., and which supposedly contains a minoramount of other higher fatty acids, etc., add an aqueous solution of onemol of ferric sulfate. Filter the precipitated water-insoluble ferricstearate, wash separately with water and alcohol, and dry at roomtemperature. The solid product softens or melts within the range of 7095C. The compound is dispersed in a solution of nitrocellulose in amixture of toluene and acetone, the amount of nitrocellulose beingone-fourth the amount 0f ferric stearate by weight, by .grinding in aball mill until a smooth coatable dispersion is obtained. The dispersionis applied to the surface of the paper by any convenient coatingprocedure, for example with a knife coater, and dried. The coated sheetis stable towards heat and light, at least to substantially the sameextent as the untreated paper.

Nitrocellulose is a preferred inert, heat-resistant binder, but otherbinder materials, e.g. ethylcellulose, polyvinyl acetate, polystyrene,and polyvinyl ybutyral are also useful. Relative amounts of binder andreactants may be widely varied. In some instances the binder may beomitted and the reactant retained within the copy sheet, being bondedand protected by the paper fibers. With larger amounts of binder it isfound desirable to employ such combinations of volatile solvents as willproduce a porous blushed binder film, thereby providing for easy accessof the reactant vapor to the coreactive ferric stearate or otherreactant material.

Pyrogallol and ferric stearate employed as hereinabove described produceintensely -colored high contrast image areas on a substantially whitebackground, with desirably high reaction speed, and at readily availabletemperatures of the order of about -150 C. Ferric soaps of otherlong-chain fatty acids are equally effective. For best results, thesematerials should be water-insoluble, and will ordinarily be found tohave a melting point within the approximate range of 70-120 C. Othervaporizable, normally stably solid phenolic reactant materials maysimilarly be substituted for the pyrogallol; catechol is one suchcompound.

The phenolic-ferric combinations will normally be found to provide adeep black or blue-black image, and therefore are highly effective forthe copying of typewritten or printed originals having a black image ona white background. For certain purposes it may be desirable to providevarious colors of images; and appropriate combinations of reactants areavailable for such purposes. For example, nickel salts, e.g. nickelacetate, in the copypaper may be reacted at image areas with vapors froma vapor supply sheet containing dimethylglyoxime or thiourea to producerespectively red or black image areas. Cobalt acetate copy paper treatedwith vapors from ammonium thiocyanate produces a -blue image; ammoniummolybdate and S-hydroxyquinoline provide a yellow image; methyl orangeand vapors from heated oxalic acid in image areas provide an orange-redimage; and a copy paper containing a colorless reaction product ofmalachite green and octadecyl amine when subjected to vapors from aheated oxalic acid-containing image provides a green image. Particularlyeffective results have also been attained using protocatechuic acid inan image vapor supply sheet and silver behenate, or a mixture of silverbehenate and behenic acid, in the coreactive receptor sheet.

In some of the foregoing, for example the pyrogallic acid and ferriestearate combination, the volatilizable reactant is transferredunchanged on heating and is directly reactive with the coreact-ant inthe copy paper, at least at suitably elevated temperatures. In othercases, such for example as the combinations including oxalic acid,gallic acid or thiourea, the volatilizable cornponent may result fromthe heat decomposition of the material initially present in the ink orin the vapor supply sheet. In all instances, however, the one reactantis transferred in vapor form to the copy sheet where the visible imageis then produced by condensation and co-reaction as indicated.

In a further modification, illustrated in FIGURE 8, an emulsion offerrie stearate was prepared in a solution of gelatin in Water and w-ascoated on an aluminum plate 25, and the coating dried to form awater-soluble layer 26. A printed page in which the printed areas werecomposed of a pigment and a nonvolatile oily binder, viz ordinaryprinting ink, was sensitized with pyrogallol vapor by heating in contactwith a vapor supply sheet as described in connection with FIGURE 1. Thethus treated original a was then placed against the dry gelatin surface26 and again heated. The pyrogallo'l vapor from the image areas enteredthe gelatin coating and reacted with the ferrie stearate, producingwater soluble materials which then reacted with the gelatin to provide acomparatively water-insoluble reaction product. The remaining areasl ofthe gelatin coating were then removed by washing with Water, leaving theinsoluble portions which corresponded with the image portions of theprinted graphic original. The plate could then be processed as alithographic plate for direct printing on untreated paper.

In FIGURE 9 the irradiation of graphic origin-al i0 causes transfer ofstrongly colored vaporizable material from vapor supply sheet 13C tountreated receptor sheet Z4, which may conveniently be a white bondpaper, to produce image-duplicating areas 20a of transferred condensateand form a right-reading reproduction of the original. Quinalizarine,green dye is one example of a strongly colored, vaporizable, normallystably solid image-forming material suitable for this use. The processis further simplified and improved by inscribing the graphicintelligence directly on the vapor supply sheet.

The use of inherently readily visible vaporizable material as describedhereinbefore in connection with FIG- URE 3, and more particularly inconnection with FIG- URE 9, permits the formation of reproductions of agraphic original on untreated receptor sheets or surfaces and withoutchemical reaction. Useful receptor sheets include untreated paper,fabric, non-woven fibrous webs, polymeric films, and metal foil. Thereceptor sheet may be treated or coated, as with pigments, fillers,binders, etc., to provide a background of increased contrast, or toassist in retaining the colored image-forming material, or for otherpurposes. The copy may also be treated or coated, eg. with small amountsof solvents or fixatives or the like to aid in retaining the coloredmaterial. No chemical reactant is necessary, however, to produce thedesired visible image; and background areas therefore remainnon-reactive.

In addition to quinalizarine green, the following dyes have been foundparticularly effective in producing reproductions of typewrittenoriginals on untreated paper receptor sheets by the method described inconnection with FIGURE 9: alizarine Irisole N; chrysoidine R; Du PontOil Blue A; Rhodamine B Extra; Ethyl Violet AX; Auramine Base; Du PontOil Orange; Du Pont Oil Yellow; Du Pont Oil Brown N; Du Pont Oil Red;Latyl Violet BN Crude; Acetamine Scarlet B; Methyl Violet 2B Base Conc.;National Indigo NACCO Pdr.; Azosol Brilliant Yellow 8 GF; Sudan Red BBA;Sudan Green 4B; and Victoria Green Base. Various mixtures andcombinations of these and other suitable dyes may also be used. Reactiveand nonreactive vaporizable components may likewise be employed inadmixture if desired.

The dyestutf has been effectively applied to a paper base by simplyswabbing the dry powder over the slightly porous surface with a cottonswab, to produce either an intermediate transfer sheet or a coatedoriginal. A preferred method involves coating one entire surface of asuitable paper with a solution of the dye in a volatile solvent, sinceimproved penetration and uniformity are thereby attained. Typically, DuPont Oil Orange is dissolved in acetone to a 10% concentration and isuniformly coated on the soft unglazed surface of thin Yankee iinispaper, which is then useful either as an intermediate vapor supply sheetor as a vapor-supplying base on which to print or type thegraphic'original.

The following specific illustrative examples will serve further todescribe the invention, which however is not to be construed as limitedthereto.

Example 1 A used lithographie plate having inked oleophilic image areason a hydrophilic treated aluminum base is placed in contact with ra drysheet of paper which has been uniformly lightly coated with pyrogallicacid. The composite is passed through a heated mangle. The paper sheetis removed and replaced with a paper receptor sheet having a thinsurface coating of ferrie stearate, and the composite again passedthrough the mangle. A mirror image of the inked image areas of thelithographic plate is visible on the coated surface and may be seen -asa direct or rightreading image from the reverse surface of thesemitransparent receptor sheet.

The same results are obtained on substituting a page of a book printedfon dense white paper for the lithographic plate.

Example 2 The lithographie plate of Example l after being heated incontact with the pyrogallic acid paper is again heated in the mangle incontact with waxed paper, a heavily parained paper commonly used as awaterproof wrapping material. The waxed paper is then placed against theferric stearate coated paper and again heated. A right-readingreproduction yof the original is obtained on the receptor sheet.

Example 3 A sheet of thin Mylar polyester film is coated at 0.6 gram persquare foot with a layer yof a mixture of silver behenate and an excessof protocatechuic acid, together with methyl methacrylate binder,applied as a dispersion in acetone. The sheet is placed against aprinted original which is then briefly irradiated with intense radiantenergy rich in infrared, forming a reproduction of the black image areasin the heat-sensitive coating. The process is wel-l known asfront-printing.

The copy is then placed with its coated surface in contact with areceptor sheet prepared by coating white paper with silver behenate in apolymeric binder. Pigments such as zinc oxide, fusible resins such asPiccolyte S-l35 polyterpene resin, and other additives are desirablyincluded but are not essential in the receptor-sheet coating. The copyis again irradiated as for thermographic copying. Controlled briefintense irradiation produces on the receptor sheet a latent image whichis thereafter made visible iby heating in an yoven or over a hot-plate;there is produced a direct reproduction of the printed original.Somewhat more drastic irradiation causes immediateformation of thevisible image on the 7 receptor sheet while still in contact with theintermediate or vapor-supply sheet.

Example 4 Thin porous paper is sparingly coated on both sides with asolution of about 20 parts of methyl gallate and one part of polyvinylacetate binder -in a solvent mixture of methylisobutylketone andalcohol. Corn starch in amount by weight equa-l to the methyl gallate isdesirably dispersed in the coating solution to overcome any tendency ofthe coating to offset, Ibut is not essential. The dry sheet is firstprinted, e.g. with a typewriter, from movable type, or in handwriting,using an ink which is infrared-absorptive. The resulting graphicoriginal, which is also a vapor supply sheet, is placed against acoreactive receptor sheet and subjected to the thermographic copyingprocedure, as described under Example 3. Up to 50 or more copies of thesame original are prepared in this way.

Example 5 Quinalizarine green base is added to a volatile liquid vehiclein amount sufficient to form a strongly colored ink which is then usedto prepare a handwritten graphic original on white paper. The driedsheet is placed with the printed surface in contact with a blank sheetof paper and the composite passed through a mangle, the back surface ofthe original contacting the heated shoe of the machine. A mirror imageof the inked areas is obtained on the receptor sheet.

Example 6 A sheet of paper is coated over a portion of one surface witha one percent solution in acetone of Du Pont Oil Orange, and over theremainder of the same surface with a similar solution of Du Pont OilBlue A. A message is printed with a typewriter on the uncoated surface.The resulting original is placed with its coated surface in `contactwith lan untreated sheet of palper, and subjected to thermographicirradiation. A copy of the message is obtained, Ibut in colorscorresponding to the location of the dye coatings.

Example 7 Thin paper is saturated with a dilute solution of Du Pont OilOrange and dried. The resulting supply sheet is placed between anuntreated paper receptor sheet and the back surface of a thin printedoriginal. The printed surface is briefly intensely irradiated with lightrich in infrared, producing a copy on the receptor sheet. Upwards of75-100 copies are produced from the same supply sheet by repeating theprocess.

Example 8 Paper is smoothly coated with a composition containing fiveparts Oil Blue A, ten parts ethyl cellulose, and five parts silica gelin acetone. The sheet is dried and placed with the coated surface incontact with a printed page, and the composite is held under moderatetension against a smooth metal surface heated to a temperature of 175 C.for five seconds. The coated sheet is replaced by a sheet of bond paperand the heating is repeated. A distinct mirror image copy of the printedcharacters is reproduced in blue on the paper.

Example 9 A page of a magazine, having blackvletters printed in varnishbase ink on a glossy white p-aper, is dipped in a dilute solution ofS-hydnoxyquinoline in acetone, drained, dried, placed on a ferricstearate receptor sheet, and ironed with a heated flatiron. A coloredreproduction of the inked areas is obtained as a reverse or mirror imageon the receptor sheet. Using the same procedure but with theS-hydroxyquinoline applied from dilute solution in car-bon tetrachlorideor toluene, a negative image is 8 obtained, the colored areas of thecopy corresponding to the unprinted background areas of the original.

Correspondingly, a dilute solution of Autol Brilliant Red BND dye intoluene applied to a printed original results in the formation of areversed negative image on ironing the treated original against a sheetof white paper.

Example 10 Thin paper is supplied on one surface with a thin coating ofisopropyl catechol and a polymeric binder. The resulting vapor supplysheet is laced with its coated Surface in contact with a sheet of paperwhich has previously been printed on the opposite surface bytypewriting, and the printed surface is briefly intensely irradiated asin thermographic reproduction procedures. The coated supply sheet isthen replaced with a receptor sheet having a surface layer of silverbehenate and polymeric binder, and the composite is again irradiatedfrom the printed surface. The printed sheet now serves as a vapor sounceor supply sheet, the vapor previously condensed therein opposite theirradiated print areas being transferred to the receptor sheet and therecondensing with the silver soap to provide corresponding visible imageareas.

In place of the untreated printed original there may be employed anink-receptive paper or other thin carrier web having on the reversesurface a thin waxy, resinous or other oleophilic coating which, likethe parain coating of the transfer sheet of Example 2, serves as atemporary reservoir for the phenolic or other vaporizable imageformingmaterial.

It will be appreciated that the vaporizable image-forming materialsemployed in the practice of this invention, whether of the reactive ornonreactive type, should be essentially nonvaporizing at normal room andstorage conditions, as indicated by the description of these materialsas normally stably solid, At the operating temperatures employed,vaporization occurs at a rate sucient to produce the desired effectwithin the limited time available in the procedures described. Infurther illustration of the vaporizability of compounds useful in thepractice of the invention, it is noted that usefully vaporizablematerials will rapidly provide sufficient vapor to actuate a test sheetwhen heated to a vaporizing temperature not higher than about 160 C. Forexample, a small quantity of Du Pont Oil Orange in an aluminum weighingdish about 1% inch deep covered with a piece of white filter paperproduced an orange-red stain on the paper when the dish was placed for afew moments on a metal test panel heated to C.

Where the appended claims call for condensing the image-forming vapor atthe receptor surface, it is to be understood that the term is employedin its broad sense, to encompass both chemical reaction resulting in anew compound, and physical conversion to a denser form of the samecompound.

There have thus been provided novel products and processes for thereproduction of printed, typed or other graphic orginals involving theheat-induced transfer of normally stably solid vaporizable image-formingmaterial in vapor form to a receptor sheet in a pattern determined bysaid original. In one embodiment, the invention involves thetransferring of a reactant vaporizable material in a patterncorresponding to the pattern of the graphic original, and the subsequentreaction of the reactant material wtih a treated or coated reactivereceptor copy sheet with which the vapor material is visibly reactive.In another embodiment the vaporizable material is itself image-forming,so that pre-treatment of the receptor sheet is rendered unnecessary. Inall cases there results a visible pattern on the receptor sheet which isidentical, either as a direct copy or as a mirror image, with thepattern of the graphic original. In addition to its application in thecopying of graphic originals having radiation-absorptive image areas,the process is applicable to the reproduction of originals prepared withspecial inks or the like containing vaporizable coloring agents orreactants, as well as to the reproduction of originals printed withresinous, oily or other image-forming ink residues and capable ofselectively accepting and at least temporarily retaining the vaporizablematerial.

What is claimed is as follows:

1. The process of reproducing a graphic original having differentiallyvapor-absorptive image and background areas comprising subjecting saidoriginal to contact with vapors from normally stably solid vaporizablereactant material for effecting absorption and concentration of saidmaterial at preferentially absorptive areas to provide a vapor supplysheet, placing said supply sheet with its treated surface against areceptor copy sheet visibly coreactive with said reactant material,heating said supply sheet at least at areas of said concentration and toan extent sufiicient to transfer said material in vapor form from saidabsorptive areas to corresponding areas of said copy sheet, andcondensing said vapor at said coreactive copy sheet.

2. The process of reproducing a graphic original comprising effecting aconcentration of normally stably solid vaporizable image-formingreactant material in a pattern corresponding to said graphi-c original,transferring said reactant material in vapor form and in said pattern toan intermediate temporary carrier sheet, placing said carrier sheet withits treated surface against a receptor copy sheet visibly coreactiveWith said reactant material, heating said carrier sheet at least atareas of said pattern and to an extent sufficient to transfer saidmaterial in vapor form from said carirer to said copy sheet, andcondensing said vapor at said coreactive copy sheet.

3. The process of reproducing a graphic original having differentiallyvapor-absorptive image and background areas comprising subjecting saidoriginal to contact with vapors of reactant material for effectingabsorption and concentration of said material at preferentiallyabsorptive areas, placing against the thus treated original anintermediate carrier sheet, heating the composite to effect transfer ofreactant material in vapor form to said carrier sheet in a patterncorresponding to said preferentially absorptive areas, placing the thustreated carrier sheet with its treated surface against a receptor copysheet visibly reactive with said material, and heating the composite oftransfer sheet and copy sheet at least at areas of said pattern and toan extent sufficient to transfer said reactant material in vapor formfrom said carrier sheet to said coreactive copy sheet in said patternand to provide a corresponding visible pattern on said receptor sheet.

4. The process of making multiple copies comprising impartingintelligence to be copied, in the form of preferentiallyradiation-absorptive image areas, to the surface of a significantly lessradiation-absorptive supply sheet having at its entire other surface alayer of normally stably solid vaporizable image-forming material,placing said supply sheet with its said other surface against a rstreceptor copy sheet and briefly exposing the inscribed surface tointense radiation to induce at said image areas a localized increase intemperature and a correspondingly localized vaporization of saidmaterial from said supply sheet to said copy sheet, with condensation atsaid copy sheet, to form a first copy, and repeating the exposure stepwith addditional receptor copy sheets to form additional copies.

5. The process of making multiple copies comprising impartingintelligence to be copied, in Ithe form of preferentiallyradiation-absorptive image areas, to the surface of a significantly lessradiation-absorptive supply sheet having at its entire other surface alayer of normally stably solid vaporizable first reactant material,placing said supply sheet with said other surface against a firstreceptor copy sheet containing a second reactant material visiblycoreactive with said first reactant and briefly exposing the inscribedsurfa-ce to intense radiation to induce at said image areas a localizedincrease in temperature and a correspondingly localized vaporization ofsaid reactant material from said supply sheet to said copy sheet, withcondensation at said copy sheet, to form a first copy, and repeating theexposure step with additional receptor copy sheets to form additionalcopies.

6. The process of making multiple copies comprising impartingintelligence to be copied, in the form of preferentiallyradiation-absorptive image areas, to the surface of a significantly lessradiation-absorptive supply sheet having at its entire other surface alayer of normally stably solid vaporizable strongly colored organic dye,placing said supply sheet with its said other surface against a firstreceptor copy sheet and briey exposing the inscribed surface to intenseradiation to induce at said image areas a localized increase intemperature and a correspondingly localized vaporization of said dyefrom said supply sheet to said copy sheet, with condensation at saidcopy sheet, to form a first copy, and repeating the exposure step withadditional receptor copy sheets to form additional copies.

7. The process of reproducing a graphic original having differentiallyvapor-absorptive image and background areas comprising subjecting saidoriginal to contact with vapors of normally stably solid Ivaporizablestrongly colored organic dye for effecting absorption and concentrationof said dye at preferentially absorptive areas to provide a vapor supplysheet, placing said supply sheet with its treated surface against thesurface of a receptor sheet, heating said supply sheet at least at areasof said concentration and to an extent suficient to transfer said dye invapor form from said absorptive areas to corresponding areas of saidreceptor sheet, and condensing said dye vapor at said receptor sheet.

8. The process of reproducing a graphic original having differentiallyradiation-absorptive image and background areas comprising brieflyintensely irradiating said original While in heat-conductive contactwith a composite of vapor supply sheet and receptor sheet in faceto-facecontact, said vapor supply sheet containing at the entire face area alayer of normally stably solid vaporizable strongly colored organic dye,the radiation inducing a selective heating effect at image areas of saidoriginal to cause a correspondingly selective transfer of said dye invapor form to said receptor sheet at said image areas, with condensationof said dye at said copy sheet.

9. The process of reproducing a graphic original having differentiallyvapor-absorptive image and background areas comprising contacting theentire face of said original with normally stably solid vaporizableimageforming material in fluid form to permit concentration of saidmaterial at preferentially absorptive areas, placing the thus treatedoriginal in face-to-face contact with a receptor surface, heating saidtreated original at least at areas of said concentration and to anextent suicient to transfer said image-forming material in vapor form tosaid receptor surface, and condensing said vapor at said receptorsurface.

10. The process of reproducing a graphic original comprising placingysaid original in heat-conductive contact with the back surface of asupply sheet having a uniform face coating of normally stably solidvaporizable strongly colored organic dye and With said supply sheet inface-to-face Contact with a receptor surface, briefly intenselyirradiating said original to cause heating of said supply sheet at imageareas of said graphic original and to an extent sufficient to transfersaid image-forming material in vapor form from the heated areas to saidreceptor surface, and condensing said vapor at said receptor surface toprovide a copy of said original having strongly colored image areas.

1l. The process of preparing a lithographie printing plate comprisingthe steps of subjecting a graphic original, having differentiallyvapor-absorptive image and background areas, to contact With vapors fromnormally stably solid vaporizable reactant material for effectingabsorption and concentration of said material at preferentiallyabsorptive areas to provide a vapor supply sheet, placing said supplysheet with its treated surface against a lithoplate master having on asupporting substrate a water-removable thin coating of a water-solublebinder `containing a icoreactant for said vaporizable reactant material,said reactarit and coreactant being -ca- -pable of interaction withformation of a reaction product which is an insolubilizing agent forsaid binder, heating said supply sheet at least at areas of saidconcentration and to an extent sufficient to transfer said material invapor form from said absorptive areas to corresponding areas of saidmaster, condensing said vapor at said Water-removable thin coating withformation of said rea-ction product and insolubilization of said binder,and then removing the unaffected portions of said coating.

References Cited by the Examiner UNITED STATES PATENTS 2,770,534 11/1956Marx. 2,798,960 7/1957 Moncretf-Yeates.

DAVID KLEIN, Primary Examiner.

11. THE PROCESS OF PREPARING A LITHOGRAPHIC PRINTING PART COMPRISING THE STEPS OF SUBJECTING A GRAPHIC ORIGINAL, HAVING DIFFERENTIALLY VAPOR-ABSORPTIVE IMAGE AND BACKGROUND AREAS, TO CONTACT WITH VAPORS FROM NORMALLY STABLY SOLID VAPORIZABLE REACTANT MATERIAL FOR EFFECTING ABSORPTION AND CONCENTRATION OF SAID MATERIAL AT PREFERENNTIALLY ABSORPTIVE AREAS TO PROVIDE A VAPOR SUPPLY SHEET, PLACING SAID SUPPLY SHEET WITH ITS TREATED SURFACE AGAINST A LITHOPLATE MASTER HAVING ON A SUPPORTING SUBSTRATE A WATER-REMOVABLE THIN COATING OF A WATER-SOLUBLE BINDER CONTAINING A COREACTANT FOR SAID VAPORIZABLE REACTANT MATERIAL, SAID REACTANT AND COREACTANT BEING CAPABLE OF INTERACTION WITH FORMATION OF A REACTION PRODUCT WHICH IS AN INSOLUBILIZING AGENT FOR SAID BINDER, HEATING SAID SUPPLY SHEET AT LEAST AT AREAS OF SAID CONCENTRATION AND TO AN EXTENT SUFFICIENT TO TRANSFER SAID MATERIAL IN VAPOR FORM FROM SAID ABSORPTIVE AREAS TO CORRESPONDING AREAS OF SAID MASTER, CONDENSING SAID VAPOR AT SAID WATER-REMOVABLE THIN COATING WITH FORMATION OF SAID REACTION PRODUCT AND INSOLUBILIZATION OF SAID BINDER, ANND THEN REMOVING THE UNAFFECTED PORTIONS OF SAID COATING. 